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WWUS20 KWNS 041845

SEL5

SPC WW 041845

DCZ000-DEZ000-MDZ000-NJZ000-PAZ000-VAZ000-WVZ000-CWZ000-050200-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 255

NWS STORM PREDICTION CENTER NORMAN OK

140 PM CDT FRI JUN 4 2010



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       DISTRICT OF COLUMBIA

       DELAWARE

       MUCH OF MARYLAND

       SOUTHERN NEW JERSEY

       SOUTHERN PENNSYLVANIA

       NORTHERN VIRGINIA

       EASTERN PANHANDLE OF WEST VIRGINIA

       COASTAL WATERS



EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 140 PM UNTIL 900

PM CDT.



HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70

MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70

STATUTE MILES EITHER SIDE OF A LINE FROM 50 MILES SOUTHWEST OF

ALTOONA PENNSYLVANIA TO 25 MILES NORTH NORTHEAST OF ATLANTIC CITY

NEW JERSEY.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE

ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).



REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE

FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY

DO PRODUCE TORNADOES.



OTHER WATCH INFORMATION...CONTINUE...WW 254...



DISCUSSION...STORMS HAVE BEEN SLOWLY DEVELOPING ALONG WEAK BOUNDARY

LOCATED IN SRN PENNSYLVANIA. MLCAPES FROM 1500-2500 J/KG AND

STRONGER FLOW LOCATED ON THE SRN FRINGE OF THE WLY/S WILL BE

FAVORABLE FOR MULTICELL STORMS WITH HAIL AND SOME WIND DAMAGE. GIVEN

THE DEEP WLY FLOW ABOVE THE BOUNDARY LAYER...THE POTENTIAL EXISTS

FOR STORMS TO EVOLVE INTO A LINE SEGMENT OR TWO...WHICH WOULD

ENHANCE THE WIND THREAT.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM

MOTION VECTOR 28020.





...IMY

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